Chapter 5 Exercise 50

50. The GEMICD9xICD10_CM crosswalk table matches the older ICD9 diagnostic codes to the newer ICD10 codes. Create a query that ignores the NoDx entries. Create a second query to find the older ICD9 codes in the VisitDiagnoses table that do not have an official match in the new ICD10 code. (Ignore the ICD10 values in the VisitDiagnoses table—which were created using this process.) Bonus: How would you find codes for the ICD9 entries that are missing cross matches?

Query1:
SELECT GEMICD9xICD10_CM.ICD9CMS, GEMICD9xICD10_CM.ICD10CM, GEMICD9xICD10_CM.MatchCode
FROM GEMICD9xICD10_CM
WHERE (((GEMICD9xICD10_CM.ICD10CM)<>"NoDx"));
SELECT VisitDiagnoses.VisitID, VisitDiagnoses.ICD10CM,
VisitDiagnoses.ICD9Diagnosis, VisitDiagnoses.Comments, Query1.ICD10CM
FROM VisitDiagnoses LEFT JOIN Query1 ON VisitDiagnoses.ICD9Diagnosis = Query1.ICD9CMS
WHERE (((Query1.ICD10CM) Is Null));